public IActionResult CalculateInterval(string formula, double?from, double?to, int?n) { if (formula == null || from == null || to == null || n == null) { var bad2 = new { status = "error", result = "wrong input" }; return(BadRequest(bad2)); } RPN rpn = new RPN(formula, (double)from, (double)to, (int)n); if (rpn.CheckInput()) { var good = new { status = "ok", result = rpn.CalculateValueOfGivenInterval() }; return(Ok(good)); } var bad = new { status = "error", result = rpn.Message() }; return(BadRequest(bad)); }